Deflection yoke

ABSTRACT

A deflection yoke with four compensation coils which are provided at the core inside which a pair of horizontal deflection coils are mounted and act on the magnetic flux generated from said horizontal deflection coils to generate a compensation field which makes the horizontal deflection field pin cushion fields at both right and left areas of the beam scanning range and a barrel field at the middle area of the range.

United States Patent lkeuchi 1 May 22, 1973 1 DEFLECTION YOKE ReferencesCited [75] Inventor: Hiroshi Ikeuchi, Yokohama, Japan UNITED STATESPATENTS Assigneel Denki ollkyo Tokyo, 3,668,580 6/1972 Barbin ..335 213Japan 3,643,192 2/1972 Chiodi .335/213 [22] Filed: Dec. 26, 1971 App].No.: 212,059

Foreign Application Priority Data 335/213; 315/27 GD, 27 XY PrimaryExaminer-George Harris Attorney -James E. Armstrong and Harold C. Wegner[57] ABSTRACT A deflection yoke with four compensation coils which areprovided at the core inside which a pair of horizontal deflection coilsare mounted and act on the magnetic flux generated from said horizontaldeflection coils to generate a compensation field which makes thehorizontal deflection field pin cushion fields at both right and leftareas of the beam scanning range and a barrel field at the middle areaof the range.

7 Claims, 11 Drawing Figures Patented May 22, 1973 3 Sheets-Sheet 1Patented May 22, 1973 3 Sheets-Sheet 2 Patented May 22, 1973 7 3,735,193

5 Sheets-Sheet 5 FIGH PRIOR ART PRIOR ART DEFLECTION YOKE BACKGROUND OFTHE INVENTION The present invention relates to the deflection yoke to beemployed in the picture tube with the so-called delta gun type in whichthree electron guns are positioned respectively at the vertexes of anequilateral triangle.

The conventional television set employing this type of the picture tubeis provided with a convergence device to converge three electron beamsinto the same hole of a shadow mask.

However, various misconvergences which are presumed to result from thedeflection field of the deflection yoke appear on the screen of thepicture tube in spite of the convergence being performed as specified inactual reception of a color television.

Of these misconvergences, the misconvergence referred to as S-ingclearly appears on a 110 deflected wide angle color TV picture tube.

The S-ing convergence is such that, as shown in FIG. 8, electron beams Rand G diverge 180 from each other on a line parallel with horizontalaxis X in reference to electron beam B even though three electron beamsB, R and G are completely converged on vertical axis Y and horizontalaxis X which pass through center of screen of the picture tube. Thismisconvergence is referred to as the S-ing misconvergence becausedivergence appears in the form of letter S.

It is known that this S-ing phenomenon can be reduced by making thedeflection field of the deflection yoke assume a pin cushiondistribution at both side areas and a barrel distribution at the middlearea of the electron beam scanning range in the emission of the electronbeams at the screen side as shown in FIG. 9. Therefore, it is proposedin conventional picture tubes to partly cut away the horizontaldeflection coil as shown in FIG. if horizontal deflection coil D of thedeflection yoke is of the saddle type and as shown in FIG. 11 if thehorizontal deflection coil is toroidally wound.

However, if this approach is employed, the deflection yoke isdisadvantageous because the distribution of the winding of thedeflection coil is complicated, mass production of the deflection yokeis difficult, the chipped portion is formed in parallel with the windingof the deflection coil and the field distribution obtained .due to thechipped portion is the same at any cross section of the deflection fieldwhereby the field distribution cannot be adjusted.

The saddle type deflection .coil is usually employed as the horizontaldeflection coil for a television. Since this type of coil is made up byforming a saddle shaped clearance in the dies for winding wire andfilling the clearance with an electric wire, it is disadvantageousbecause it is difficult to form the chipped portion as shown.

The present invention provides a deflect-ion yoke free from thedisadvantages described above.

SUMMARY The deflection yoke according to the present invention iscomprised of a pair of the toroidal type or saddle type verticaldeflection coils, apair of the toroidal type or saddle type horizontaldeflection coils, a core ,provided with said deflection coils, and fourtoroidal type or saddle type compensation coils provided at said core,wherein said compensation coils are overlapped on part of a pair ofhorizontal deflection coils and are arranged so as to produce magneticfluxes which compensate the horizontal deflection magnetic fieldgenerated by the horizontal deflection coils, said compensation coilsbeing respectively arranged symmetrically at both sides of eachhorizontal deflection coil in reference to the center line of thehorizontal deflection coil and, at the same time, being positioned sothat the deflection magnetic field of the horizontal deflection coils iscompensated to the pin cushion fields at both side areas of the electronbeam scanning range and to a barrel field at the middle area of thescanning range.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is illustratedin detail by the accompanying drawings whereon:

FIG. 1 is a plan view of a deflection yoke according to the presentinvention,

FIG. 2 is a magnified cross sectional front view along line IIII in FIG.1,

FIG. 3 is an explanatory view of horizontal deflection magnetic fieldformed by this deflection yoke,

FIGS. 4 and 5 are plan views of the core illustrating the arrangement ofcompensation coils of this deflection yoke.

FIG. 6 is a circuit diagram of the compensation coil showing the otherembodiment of this deflection yoke,

FIG. 7 is a diagram showing the waveform of the current to be suppliedto the compensation coils shown in FIG. 6,

FIG. 8 is an explanatory view of the S-ing misconvergence by theconventional deflection yoke,

FIG. 9 is an explanatory view of the horizontal deflection magneticfield which compensates said S-ing misconvergence, and

FIGS. 10 and 11 are plan views illustrating conventional horizontaldeflection coils.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2, there is showndeflection yoke 1 comprised of a pair of toroidal-type verticaldeflection coils 2, a pair of saddle-type'horizontal deflection coils 3,cylindrical core 4 around which said vertical deflection coils arewound, horn shaped bobbin 5 which is mounted on said core and isprovided with horizontal deflection coils 3 at its inside surface, fourcompensation coils 6 which are wound around core 4, clamp belt 7 whichclamps the core, flange 8 attached to the rear part of the core and aplurality of clamping segments 9 extended from the flange toward therear side along the neck of the picture tube (not shown).

In this embodiment, compensation coils 6 are wound together with saidvertical deflection coils 2 around core 4. Each compensation coil 6 issymmetrically wound in reference to center line L of each horizontaldeflection coil 3 and is arranged so as to be overlapped with part ofeach horizontal deflection coil 3.

Compensation coils 6 are made to generate magnetic fluxes which offsetpartly the magnetic flux from horizontal deflection coils 3;accordingly, the compensation coils generate the magnetic fluxes in thedirection opposite the magnetic flux generated from horizontaldeflection coils 3.

Such oppositely oriented magnetic fluxes can be easily generated fromthe compensation coils by reversing the winding direction of eachcompensation coil or by selecting the direction of the current suppliedto the compensation coils.

Referring to FIG. 3, there is shown a horizontal deflection magneticfield generated by horizontal deflection coils 3 and compensation coils6.

If the magnetic fluxes from compensation coils 6 are not considered, thehorizontal deflection magnetic field forms a conventional uniformmagnetic field as shown with dotted lines. If the compensation magneticfields of compensation coils 6 which are formed as shown with brokenlines are applied to said magnetic field, part of the main deflectionmagnetic field from the horizontal deflection coils is offset by thecompensation magnetic fields whereby the horizontal deflection magneticfield shows pin cushion distribution at both right and left side areasof the scanning range of the beams as shown with solid lines and abarrel distribution at the middle area of the scanning range. In otherwords, the horizontal deflection magnetic field which is desirable tocompensate the S-ing misconvergence is formed in the magnetic fieldsgenerated by compensation coils 6.

The saddle type coil can be used as the compensation coils. In thiscase, four saddle type coils are arranged as in case of said embodiment.

If the compensation coils are wound in the reverse direction to thehorizontal deflection coils, the horizontal deflection current can besupplied to compensation coils 6. In this case, the compensation coilscan be connected in series and then can be connected in series to thehorizontal deflection coils.

The ratio of the currents supplied to the horizontal deflection coilsand the compensation coils can be predetermined; however, it isdesirable to adjust the ratio of these currents by providing the currentdistributor in the circuit.

Thus, asymmetrical distortion due to error of the coil arrangementoccurring in manufacturing the deflection yoke can be compensated.

If said current distributor can vary the ratio of the currents to besupplied to the compensation coils and the horizontal deflection coilsduring the scanning period, the distortion can be further rigorouslycompensated.

Compensation coils 6 need always not operate so as to offset themagnetic flux from horizontal deflection coils. If the horizontaldeflection magnetic field shows a pin cushion distribution, the magneticflux generated from compensation coils 6 can be superposed with themagnetic flux generated from the horizontal deflection coils.

In this case, the magnetic field generated by compensation coils 6 showsbarrel distribution.

If the horizontal deflection magnetic field shows similarly the barreldistribution, the pin cushion distribution magnetic field may be formedby compensation coils 6.

However, as is well known, in case of the wide angle color picture tube,the integrated value of the horizontal deflection magnetic fields inplanes intersecting at a right angle to the axial direction of the beamemission is made to cause a slight pin cushion type distribution toimprove the convergence characteristic against divergence of threebeams; accordingly, the horizontal deflection magnetic field may beactually a uniform magnetic field and a pin cushion distributionmagnetic field.

If horizontal deflection coils 3 form a uniform magnetic field,compensation coils 6 are wound around core 4 as shown in FIG. 4.

Compensation coils 6 are positioned on outer side to be remote from eachother at front side 31 of each horizontal deflection coil 3, that is, atthe screen side of the picture tube, to offset the magnetic flux fromthe horizontal deflection coils and to form the deflection magneticfield as shown in FIG. 3, while it offsets the magnetic flux at themiddle of the horizontal deflection field at rear side 32 of eachhorizontal deflection coil 3, that is, at the electron gun side of thepicture tube and forms the pin cushion type magnetic field. On the otherhand, if horizontal deflection coils 3 generate a pin cushion typemagnetic field, compensation coils 6 are around core 4 so that they neareach other at front side 31 of each horizontal deflection coil and areremote each other at rear side 32 as shown in FIG. 5.

In this embodiment compensation coils 6 are designed to generatemagnetic fluxes in the same direction as horizontal deflection coils 3.Accordingly, the magnetic field formed by the horizontal deflectioncoils tend to show the barrel distribution at the front middle and thepin cushion distribution at the rear side area.

In this embodiment, the deflection yoke is advantageous because theaforementioned integration value of the horizontal deflection magneticfields of deflection yoke 1 shows the pin cushion distribution, whereasit forms the deflection magnetic field at the screen side as shown inFIG. 9.

The deflection yoke according to the present invention is advantageousbecause the horizontal deflection magnetic field is compensated bycompensation coils, the production of the deflection yokes is easy andthe distribution of horizontal deflection magnetic field can be freelycompensated.

Because said compensation coils cause the magnetic fields to act on thedeflection magnetic field, they can compensate deflection distortion,which is different from the S-ing misconvergence, together with theS-ing misconvergence.

Compensation coils 6 shown in FIG. 6 are designed to compensate theS-ing misconvergence and, at the same time, to compensate the divergenceposition of three electron beams B, G and R. The following describes thedivergence positions of three electron beams. As is shown fromcontemporary research, it is desirable for convergence withoutdeterioration of the purity to diverge three electron beams so that theelectron beams are respectively positioned at the vertexes of anequilateral triangle at any position on the screen of the picture tube.However, in case of the wide angle deflection picture tube, it isinevitable that the spot positions of three electron beams correspond tothe vertexes of a scalene triangle at the positions near the top,bottom, right side and left side areas of the screen, due to thecurvature of the screen. Accordingly, the deflection yoke isdisadvantageous because the purity deteriorates due to convergence.

Four compensation coils 6 shown in FIG. 6 are divided into a pair ofgroups 6' containing two coils which are series connected and each groupis parallel connected to power supply 10. These four compensation coils6 are series connected to another power supply 11.

If power supply 10 is the deflection current source and the compensationcurrent which has large amplitude at the initial stage and the finalstage of vertical deflection period IV as shown in FIG. 7 and the samephase as the horizontal deflection current is supplied from other powersupply 11, compensation coils 6 generate field f shown with dotted linesand fields f shown with broken lines. As described above, field, f,shown with dotted lines is effective to compensate the S-ingmisconvergence, and fields f shown with broken lines acts to shiftelectron beams G and R in the horizontal deflection magnetic field.

Accordingly, with fields f the positions of two electron beams G and Rcan be shifted in reference to beam B which is positioned in thevertical direction and thus the positions of three electron beams can beadjusted with the compensation current from power supply 11 so that thespots of three electron beams are positioned respectively at vertexes ofan equilateral triangle on the screen of the picture tube.

For such adjustment, however, the positions of three electron beamsshould be pre-adjusted so that the spots of three electron beams arerespectively positioned at the vertexes of an equilateral triangle at acertain area on the screen and at the vertexes of an isosceles triangleat the other area on the screen. In addition, this preadjustment can beeasily done.

Either of said power supplies l0 and 11 may be the horizontal deflectioncurrent source and the rest of power supplies may be selected accordingto the purpose of compensation of distortions except for the S-ingmisconvergence.

What we claim is:

l. A deflection yoke comprised of a. a pair of vertical deflectioncoils,

b. a pair of horizontal deflection coils,

c. a core on which said deflection coils are mounted and d. fourcompensation coils which are arranged symmetrically in reference to thecenter line of each horizontal deflection coil, wherein saidcompensation coils are overlapped on part of said horizontal deflectioncoils respectively and are arranged to generate magnetic fluxes whichcause the main deflection magnetic field generated from said horizontaldeflection coils to be adjusted to show pin cushion distribution at bothright and left side areas of the beam scanning range and to show barreldistribution at the middle area of said range, said horizontaldeflection coils adapted to generate a uniform main deflection magneticfield and said compensation coils adapted to generate compensationmagnetic fluxes which flow in the direction opposite the magnetic fluxof said main deflection magnetic field.

2. A deflection yoke according to claim 1 wherein a horizontaldeflection source is connected to said compensation coils.

3. A deflection yoke according to claim 2 wherein a current distributoris provided to vary the ratio of the horizontal deflection currentsupplied to said compensation coils and said horizontal deflectioncoils.

4. A deflection yoke according to claim 3 wherein said compensationcoils are connected in series and the serially connected compensationcoils are further connected in series with said horizontal deflectioncoils.

5. A deflection yoke according to claim I wherein said compensationcoils are remote from each other at the front side of each horizontaldeflection coil and closer to each other at the rear side of eachhorizontal deflection coil and are near to each other at the rear sideof each horizontal deflection coil. 6. A deflection yoke comprised of a.a pair of vertical deflection coils, b. a pair of horizontal deflectioncoils, c. a core on which said deflection coils are mounted and d. fourcompensation coils which are arranged symmetrically in reference to thecenter line of each horizontal deflection coil, wherein saidcompensation coils are overlapped on part of said horizontal deflectioncoils respectively and are arranged to generate magnetic fluxes whichcause the main deflection magnetic field generated from said horizontaldeflection coils to be adjusted to show pin cushion distribution at bothright and left side areas of the beam scanning range and to show barreldistribution at the middle area of said range, said horizontaldeflection coils being designed so that the main deflection magneticfield generated by said horizontal deflection coils presents pin cushiontype distribution, said compensation coils being arranged so that thecoils are near each other at the front side of each horizontaldeflection coil and are remote from each other at the rear side of saidhorizontal deflection coil, said compensation coils being designed togenerate magnetic fluxes which flow in the same direction as themagnetic flux of the horizontal deflection coils whereby the magneticfields of said compensation coils is superposed on the main deflectionmagnetic field. 7. A deflection yoke comprised of a. a pair of verticaldeflection coils b. a pair of horizontal deflection coils, c. a core onwhich said deflection coils are mounted and d. four compensation coilswhich are arranged symmetrically in reference to the center line of eachhorizontal deflection coil, wherein said compensation coils areoverlapped on part of said horizontal deflection coils respectively andare arranged to generate magnetic fluxes which cause the main deflectionmagnetic field generated from said horizontal deflection coils to beadjusted to show pin cushion distribution at both right and left sideareas of the beam scanning range and to show barrel distribution at themiddle area of said range, said four compensation coils being seriesconnected in' a pair of groups respectively containing two coils, saidcoil groups being parallel connected to one power supply, said fourcompensation coils being series connected to another power supply, oneof said two power supplies being adapted to cause said compensationcoils to generate magnetic fields which make the main deflectionmagnetic field to show pin cushion distribution at both right and leftside areas of the beam scanning range and barrel distribution at themiddle area of said range and the other power supply being adapted tocause said compensation coils to generate magnetic fields which shifttwo of three electron beams except for a beam in the vertical directionin the horizontal deflection magnetic field.

1. A deflection yoke comprised of a. a pair of vertical deflectioncoils, b. a pair of horizontal deflection coils, c. a core on which saiddeflection coils are mounted and d. four compensation coils which arearranged symmetrically in reference to the center line of eachhorizontal deflection coil, wherein said compensation coils areoverlapped on part of said horizontal deflection coils respectively andare arranged to generate magnetic fluxes which cause the main deflectionmagnetic field generated from said horizontal deflection coils to beadjusted to show pin cushion distribution at both right and left sideareas of the beam scanning range and to show barrel distribution at themiddle area of said range, said horizontal deflection coils adapted togenerate a uniform main deflection magnetic field and said compensationcoils adapted to generate compensation magnetic fluxes which flow in thedirection opposite the magnetic flux of said main deflection magneticfield.
 2. A deflection yoke according to claim 1 wherein a horizontaldeflection source is connected to said compensation coils.
 3. Adeflection yoke according to claim 2 wherein a current distributor isprovided to vary the ratio of the horizontal deflection current suppliedto said compensation coils and said horizontal deflection coils.
 4. Adeflection yoke according to claim 3 wherein said compensation coils areconnected in series and the serially connected compensation coils arefurther connected in series with said horizontal deflection coils.
 5. Adeflection yoke according to claim 1 wherein said compensation coils areremote from each other at the front side of each horizontal deflectioncoil and closer to each other at the rear side of each horizontaldeflection coil and are near to each other at the rear side of eachhorizontal deflection coil.
 6. A deflection yoke comprised of a. a pairof vertical deflection coils, b. a pair of horizontal deflection coils,c. a core on which said deflection coils are mounted and d. fourcompensation coils which are arranged symmetrically in reference to thecenter line of each horizontal deflection coil, wherein saidcompensation coils are overlapped on part of said horizontal deflectioncoils respectively and are arranged to generate magnetic fluxes whichcause the main deflection magnetic field generated from said horizontaldeflection coils to be adjusted to show pin cushion distribution at bothright and left side areas of the beam scanning range and to show barreldistribution at the middle area of said range, said horizontaldeflection coils being designed so that the main deflection magneticfield generated by said horizontal deflection coils presents pin cushiontype distribution, said compensation coils being arranged so that thecoils are near each other at the front side of each horizontaldeflection coil and are remote from each other at the rear side of saidhorizontal deflection coil, said compensation coils being designed togenerate magnetic fluxes which flow in the same direction as themagnetic flux of the horizontal deflection coils whereby the magneticfields of said compensation coils is superposed on the main deflectionmagnetic field.
 7. A deflection yoke comprised of a. a pair of verticaldeflection coils b. a pair of horizontal deflection coils, c. a core onwhich said deflection coils are mounted and d. four compensation coilswhich are arranged symmetrically in reference to the center line of eachhorizontal deflection coil, wherein said compensation coils areoverlapped on part of said horizontal deflection coils respectively andare arranged to generate magnetic fluxes which cause the main deflectionmagnetic field generated from said horizontal deflection coils to beadjusted to show pin cushion distribution at both right and left sideareas of the beam scanning range and to show barrel distribution at themiddle area of said range, said four compensation coils being series -connected in a pair of groups respectively containing two coils, saidcoil groups being parallel - connected to one power supply, said fourcompensation coils being series - connected to another power supply, oneof said two power supplies being adapTed to cause said compensationcoils to generate magnetic fields which make the main deflectionmagnetic field to show pin cushion distribution at both right and leftside areas of the beam scanning range and barrel distribution at themiddle area of said range and the other power supply being adapted tocause said compensation coils to generate magnetic fields which shifttwo of three electron beams except for a beam in the vertical directionin the horizontal deflection magnetic field.